To cope with malignant tumors which cannot be excised, chemotherapy by anti-cancer drug administration has been practiced. However, since systemic administration of the drug causes serious side reactions, methods of selective administration have been used in which either the tip of a catheter is kept staying at the upper stream of the artery which leads to the site of the tumor while the end of the catheter is kept exposed outside the body as the inlet of the anti-cancer drug, or the catheter is re-inserted at each time of anti-cancer drug administration (intra-arterial therapy). In sustained injection of a high calorie infusion solution previously used, also, the tip of the catheter was kept staying in the central vein and the end of the catheter was exposed outside the body as the inlet of the fluid therapy injection (IVH).
Consequently, the prevention of infection through the wound of the skin at which the catheter has been inserted has been a long-standing problem. On the other hand, it is very difficult to keep the wounded part of the skin always clean in practical life; moreover, the presence of the catheter and the wound imposes restriction to the free movement, bathing, etc. of the patient. Thus, these situations have been a serious obstacle to the returning of the patient to the public community.
To solve the above-mentioned problems, a catheter assembly of subcutaneous imbedding type which can be used while being kept staying in the body for a long period has been developed. This catheter assembly comprises a port main body having an internal space for storing a medicinal liquid, a medicinal liquid inlet provided with an elastic body which communicates with the internal space, and a medicinal liquid outflow path provided with a connector, and a catheter having a lumen for medicinal liquid injection formed therein, the catheter being joined to the connector such that the lumen communicates with the liquid outflow path, and a protective lock for fixing the catheter and preventing it from kinking (folding) being joined by fitting thereto so as to cover the catheter joining part of the port main body.
The catheter assembly of subcutaneous imbedding type is kept in the body at a state wherein the catheter is inserted into the intended blood vessel and the medicinal liquid injection port is fixed in the subcutaneous tissue. In injecting a medicinal liquid, the medicinal liquid inlet of the liquid injection port is confirmed by palpation on the skin surface and the elastic body of the liquid inlet is needled with an injection needle thereby to feed the medicinal liquid into the port main body and inject the liquid into the intended blood vessel or the like via the catheter.
In the catheter assembly of the prior art, however, the connector is attached to the outer periphery of the port main body and resultantly the protective lock, which is connected and fixed by means of screw fitting, etc., protrudes further than the end of the connector to prevent the kink of the catheter which might be caused by the tip of the connector. Accordingly, when the catheter assembly of subcutaneous imbedding type is imbedded subcutaneously, an imbedding space which can accommodate only the periphery of the port main body is insufficient for the purpose and a deep incision must be made which corresponds to the space including the protective lock on the vertical line of the catheter. This not only imposes a heavy burden on the patient but makes it difficult for the operator to confirm the medicinal liquid inlet. Moreover, the longer the line including the port main body and the protective lock (that is, the longer the hard parts), the more difficult for the assembly to follow the movement of the patient, resulting in increased risk of occurrence of various troubles, such as the kink of the catheter.
The sites in which the medicinal liquid injection port is to be imbedded are mainly the chest, abdomen and thigh. In recent years, both the intra-arterial therapy and the IVH are mainly conducted by making use of the subclavian artery or vein and hence the port is mainly imbedded in the chest region.
When the medicinal liquid injection port of the prior art is viewed from side, the upper face is convex and the bottom face is flat. FIG. 5 is a sectional view of the prior medicinal liquid injection port imbedded subcutaneously, which shows a considerable protrusion of the skin. This causes much invasion when the injection port is imbedded in a site with thin subcutaneous fat, such as the chest region. Particularly when it is imbedded to a slender patient, the top of the skin is rubbed by clothes, which often causes rubefaction and inflammation.